60-700 K CTAT and PTAT Temperature Sensors with 4H-SiC Schottky Diodes.

Razvan Pascu,Gheorghe Pristavu,Philippe Godignon,Matei Serbanescu,Adrian Tulbure,Florin Draghici,Cosmin Romanitan,Gheorghe Brezeanu

doi:10.3390/s21030942

Abstract

A SiC Schottky dual-diode temperature-sensing element, suitable for both complementary variation of VF with absolute temperature (CTAT) and differential proportional to absolute temperature (PTAT) sensors, is demonstrated over 60–700 K, currently the widest range reported. The structure’s layout places the two identical diodes in close, symmetrical proximity. A stable and high-barrier Schottky contact based on Ni, annealed at 750 °C, is used. XRD analysis evinced the even distribution of Ni2Si over the entire Schottky contact area. Forward measurements in the 60–700 K range indicate nearly identical characteristics for the dual-diodes, with only minor inhomogeneity. Our parallel diode (p-diode) model is used to parameterize experimental curves and evaluate sensing performances over this far-reaching domain. High sensitivity, upwards of 2.32 mV/K, is obtained, with satisfactory linearity (R2 reaching 99.80%) for the CTAT sensor, even down to 60 K. The PTAT differential version boasts increased linearity, up to 99.95%. The lower sensitivity is, in this case, compensated by using a high-performing, low-cost readout circuit, leading to a peak 14.91 mV/K, without influencing linearity.

Highlights

Space missions, automotive, and various industries involve applications with a wide thermal variation and a large temperature range for detection
The most promising candidate for high temperature silicon carbide (SiC) Schottky diode-based sensors is Ni, due to its high work function and the capability to form very stable nickel silicide compounds on SiC after rapid post-metallization annealing in inert atmospheres [31]
With the proposal of differential measurement techniques for SiC-Schottky diode temperature sensors [28,39], which considerably increase sensing linearity, as well as the recent introduction of a practical inhomogeneity modeling technique [40], the premises are set for investigating the potential performances of these devices over ranges spanning from cryogenic levels to high-temperature domains

Summary

Introduction

Automotive, and various industries involve applications with a wide thermal variation and a large temperature range for detection. When working in such hostile environments, the performances of conventional sensing solutions can be affected by accuracy degradation or worse, general failure [1,2] These detection systems include a series of commercial temperature sensors, which are based on thermocouples [3] or resistive temperature detectors [4,5]. The most promising candidate for high temperature SiC Schottky diode-based sensors is Ni, due to its high work function and the capability to form very stable nickel silicide compounds on SiC after rapid post-metallization annealing in inert atmospheres [31] It ensures a reasonably constant SBH, with values upwards of 1.73 V, for wide temperature ranges [25]. With the proposal of differential measurement techniques for SiC-Schottky diode temperature sensors [28,39], which considerably increase sensing linearity, as well as the recent introduction of a practical inhomogeneity modeling technique [40], the premises are set for investigating the potential performances of these devices over ranges spanning from cryogenic levels to high-temperature domains

Methods

Results

Conclusion